[unreadable] The long-range goal of this application is to determine the factors that predict the manner in which pathogenesis develops during poly-microbial infections. The short-term goal of this project will be to determine the manner in which BCG-associated inflammation and its modulation of antigen presenting cells affects a new immune response to a vaccine antigen delivered as and inactivated organism. Our preliminary studies support our goals and application by establishing a link between innate DC dysfunction and lower adaptive responses to vaccine antigens delivered as an inactivated organism during an ongoing bacterial infection. Based on our preliminary observations, we hypothesize that a decreased potential to develop protective immune responses during Mycobacterial infection is due to a cyclic period of down-regulation of accessory cell function and a decrease of CD11c cell subsets. We will test this hypothesis by defining immune correlates and gene expression patterns within CD11c+ and CD11b+ accessory cell subsets during BCG infection through [1] longitudinal analysis of the changes in B-cell proliferation, T -cell activation, DC cell subsets, DC activation (CD86, CD80, CD40, CD95, MHC-II) and function (MLR, endocytosis, TLR-4 induced IL-12p70, IL-I0, TNF-a secretion), and RNA gene expression of sorted CD11c+CD11b+ or CD 11c+CD 11 b+ DC subsets from longitudinal time points by cDNA microarrays of un-stimulated and in vitro stimulated cultures; and [2] establishing the biological impact of accessory cell changes due to primary BCG infection on the development of secondary anti-flu responses by analysis of the development and recruitment of antiviral humoral and cell-mediated immune memory responses acquired through UV inactivated Influenza A/PR8 vaccination of naive or BCG-infected animals at weekly intervals throughout BCG infection. We apply a vaccine approach within an on-going bacterial infection as a surrogate method to elicit a primary immune response and its associated memory pools with minimal pathology or additional pathogen co-factors. We will compare morbidity and mortality outcomes to developing antiviral immune responses following live challenge of animals having received vaccination against Influenza A/PR8 at different periods of BCG infection and clearance. Completion of this application will provide identify innovative targets for increased susceptibility to bacterial/viral co-infections by addressing understudied areas of innate immunity and chronic inflammation as central factors to decreased adaptive responses and protective immunity. This application represents a collaborative effort by The Wistar Institute and the Department of Dermatology, and the Center for Clinical Epidemiology and Biostatistics from the University of Pennsylvania. [unreadable] [unreadable]